Vehicles often operate in either a key-on or a key-off state. In the key-on state, an engine or motor of the vehicle is running and supplies full power to any active vehicle system. In the key-off state, an occupant has turned off the engine or motor, and a battery of the vehicle supplies power to select systems, such as a clock or a security alarm. A vehicle may be equipped with impact sensors that operate while the vehicle is in the key-on state. The impact sensors are adapted to detect an impact to the vehicle. The impact sensors may be located at numerous points in or on the vehicle. Some impact sensors are post-contact sensors such as accelerometers, pressure sensors, and contact switches; and pre-impact sensors such as radar, lidar, and vision-sensing systems. Vision systems include one or more cameras, CCD image sensors, CMOS image sensors, etc.